This invention relates to an outboard motor, and more particularly, to an improved outboard motor having a compact configuration with an improved exhaust having improved silencing characteristics.
Conventional outboard motors generally are affixed so that they extend just rearwardly of the transom of a watercraft and include a driveshaft housing in which a vertically positioned driveshaft is journaled for driving a propulsion unit in the lower unit to propel the watercraft. An internal combustion engine is normally mounted in a power head above the driveshaft housing and has its output shaft directly coupled to the drive-shaft for driving the propulsion unit. Consequently, the exhaust system is typically shortened, rigid, and movable with the engine and lower drive unit. Although this type of construction has advantages, it tends to severely restrict the overall length and configuration of the exhaust system. Such restricted length and configuration inhibits the tunability of the exhaust path and degrade engine performance both in terms of engine efficiency and the excess noise produced by the engine. In addition, a shorter exhaust path reduces the opportunity for adequate exhaust gas cooling before the exhaust gases are expelled.